Based on the short story "The Playground" by Ray Bradbury. The story was first published in Esquire (October 1953).

Host: You know it's amazing how fond I've become of the sound of this typewriter's, ah, till the power fails, very comforting. (lights candle) Well like a night-light when we were kids in a dark room. Remember how it used to be? When we'd wander around our homes and be terrified of the littlest things. Of course it's not true for us nowadays. At the moments like this what we long for is an old warm friend and I have one right here. (accidentally blows out camera) Damn.

Charles Underhill: You should have seen it. Smelled it, heard it. The playground stinks of tennis shoes, blood, dirty bandages. Their mean little faces, with green jelly running out of their noses.

Charles Underhill: Bob, tell me...
Robert Peerless: Yeah, Charlie?
Charles Underhill: How do you raise a boy?
Robert Peerless: Geez, I don't know. What? I mean, you find a cement mixer, you throw him in, you let it run for five minutes, you take him out.

Changes from the short story:

* In the original story, the playground is more of a "personality," and an unseen manager is implied to be the source of the transformations.
* Charles deliberately chooses to trade places with his son, an exchange that is not made clear in the episode itself.